Underlying Mitt Romney’s defeat Tuesday in the presidential election are some unsettling demographic trends for the Grand Old Party, whose base of support continues to be the nation’s declining white population.

President Obama’s campaign exploited the incremental increases in Latinos, Asian-Americans, and voters under the age of 30 to consolidate most of the gains made in the Democratic Party’s electoral expansion four years ago.

“There’s no arguing with the demographic changes — they’re clear,” said Scott Keeter, director of survey research at the Pew Research Center and an exit poll analyst for NBC. “Any way you cut it, white non-Hispanics are going to become an ever decreasing share of the US population. In some respects, the Electoral College magnifies that impact, because a number of key states a candidate needs to amass an electoral majority are already ahead of the national average of the percentage of nonwhites.”

William H. Frey, a demographer at the Brookings Institution, a nonpartisan think tank, attributed Romney’s defeat to his party’s inattention to Latinos, a record 10 percent of Tuesday’s electorate. They voted for Obama, 71 percent to 27 percent, according to exit polls.

“It seems to me that the Republican Party could have easily won that election,’’ Frey said. “They should at least pay attention to the concerns of Hispanics.”

Many Republican Party policies could appeal to Hispanics, such as tax breaks for small businesses and family issues, Frey said.

“But if you completely slough it off and talk about deporting people, you’re throwing it in people’s faces,” he said.

One problem for the GOP, a specialist says, is its predominantly white face.

Republicans have won the white vote in every presidential election since 1964, and that continued Tuesday with Romney beating Obama by 20 points, 59 percent to 39 percent, according to exit polls. But the percentage of white voters was 72 percent, down from 74 percent in 2008. It has dropped in all but one of the nine elections since 1976, when it was 89 percent.

At the same time, Obama won 80 percent of the minority vote, which, besides Latinos, included African Americans, 13 percent of turnout, the same as 2008, and Asian-Americans, who were 3 percent of the vote, up a point from the last election.

The political fallout of this was clear: Although Romney narrowly lost the popular vote, he was decisively defeated in the Electoral College, as Colorado and Nevada, almost always reliably Republican for the past four decades, went Democratic for the second straight election.

They join Virginia and North Carolina as newly winnable states for Democrats. Both have large black populations, along with a large population of transplants from other parts of the country. Obama won Virginia for the second time Tuesday but narrowly lost North Carolina, which he barely carried in 2008.

These are merely the latest manifestations of gradual demographic trends. Based on Census Bureau estimates, the nation’s white population, which was 85 percent in 1960 and 63 percent in 2011, will drop to minority status, about 47 percent, in 2050. Latino population, only 3.5 percent in 1960 and 17 percent last year, is projected to rise to 29 percent by then, while Asian-Americans, less than one percent 52 years ago and 5 percent last year, is seen as rising to 9 percent in 2050. The trend of fast-rising Latino population is happening in other traditionally Republican states such as Arizona and Texas.

One problem for Republicans is the very white public face of the party, said Clara Rodriguez, professor of sociology at Fordham University. Latinos and other minorities also care about jobs and housing, and some embrace the Republican belief in limited government, she said. But they do not see a welcoming presence at party events.

“I do think that the message you get when just about every person you see at a Republican rally is white, that it essentially proves the rule that those representing the Republican Party are white,” Rodriguez said.

Compounding problems for the GOP is the distinct tilt of voters under the age of 30 toward the Democrats in recent years.

Rodriguez and Frey both said the so-called millenials, who are ages 18 to 29, are products of a much more racially and culturally diverse society than their parents, and it is reflected in their voting propensities.

“They grew up past the Reagan era, in the 1990s, when Clinton was president,’’ Frey said.

“More liberal issues were coming to the fore and the climate was more racially and ethnically diverse and they tend to be more tolerant on issues like mixed-racial marriage or gay rights. It is something that makes them more liberal and Democratic leaning.”

“The fact that the turnout was no lower than four years ago is pretty significant, especially given the fact that a lot of observers, including myself, predicted that the youth turnout would be down this year” because of the effects of the economy on their employment prospects, Keeter said.

“I think a lot of people thought it was all about Obama in 2008, but that’s not really true. I think he was able to take advantage of a trend that was already there and even intensify it.”